Detecting individual short circuits and locating these short circuits in chains of series-connected electrical loads is useful for a variety of applications. These applications include Light-Emitting Diode (LED) chains for automobile displays, personal computer displays, and LED backlighting systems.
Typical LED power supplies may include an LED driver, one or more LED chains, and in some cases a short-circuit detection circuit. The LED driver provides current to the LEDs in the LED chains, and the LEDs have a forward voltage across them in the direction of current flow. An LED chain has a voltage across it that is the sum of the forward voltages of the LEDs making up the chain. The short-circuit detection circuit detects whether a short circuit has occurred in the LED chains. Some implementations use a per-chain dedicated control pin to change the sensing point of the short-circuit detection circuit relative to the LED chains.